Stripper spring unit for presses



July 14, 1964 L. H. WOLF STRIPPER SPRING UNIT FOR PRESSES Filed oct'. 31, i960 ze W ff 247 L4 20@ l 2f H-`* /1/.zf

m LQ* F1 f f 28 *.9* 3 a, 29 a 13 ,l 42 30 34 '325,33 .as :d 16 44* I 70 )r 'v l W4 I 'fe 24T LA? 'i 40 1; .38 NIl N '0 mmm was United States Patent O 3,146,630 STEUDPER SPG UNT FR PRESSES Lewis H. Wolf, 58 rehard Drive, Kenmore, NY. Filed (Eet. 31, 1960, Ser. No. 66,276 6 Claims. (Qi. S3--ll4tl) This invention relates to a stripper spring unit for supporting and actuating the stripper plate of a press to strip the workpiece from the punches following the punching operation.

An important object of the invention is to provide such stripper spring units which permit complete removal of the stripper plate without change in adjustment or without change in position of those parts of the stripper spring units which remain attached to the shoe carrying the stripper spring units. Accordingly, in the event of a broken punch or any required resharpening, dressing or alteration in the number or position of the punches, all that is required is to remove the stripper plate, perform the necessary operations on the punch or punches and replace the stripper plate, there being no necessity for readjusting or repositioning any of the parts of the stripper spring units which remain attached to the shoe carrying the punches.

Another important object of the invention is to provide such a stripper spring unit in which spring breakage is reduced to a minimum, it being a feature of the invention that the springs can be selected or tailored to` the exact requirement of any particular operation.

Another important object of the invention is to provide such `a stripper spring unit which is composed of standard parts commercially available in quantity on the open market,

Another object is to provide such a stripper spring unit which is of simple and strong construction and in which the stripper plate can be removed by the removal of one attaching screw of each stripper spring unit, this attaching screw screwing into the same threaded bore as the stripper bolt.

Other objects and advantages of the invention will be apparent from the following description and drawings in which:

FIG. l is a fragmentary vertical section, partly in elevation, of a stripper spring unit embodying the present invention, and showing the same operatively associated with the stripper plate, top shoe, a punch, a workpiece to be formed, and a die.

FIG, 2 is a fragmentary view similar to FIG. l but showing the stripper plate and parts of the stripper spring unit in exploded relation to illustrate the manner in which the stripper plate can be removed without disturbing the adjustment of the stripper spring and without disturbing the position of those parts of the spring unit which remain attached to the top shoe.

FTG. 3 is a fragmentary horizontal section taken generally on line 3 3, FIG. l.

The stripper spring unit forming the subject of the present invention is shown in conjunction with a conventional stripper plate 1t) and a conventional top shoe 11, the latter being secured to the underside of a ram 12 of the press in any conventional manner. The top shoe is illustrated as carrying a punch 13 which is shown las secured to the underside of the shoe by means of a conventional attaching block 14. While the punch 13 is shown as being in the form of a perforating punch, it will be understood that it could also be `any other form of punch such as a blanking punch, forming punch, notching punch or any other form of punch.

The punch 13 is shown as working through a hole 1S in the stripper plate against the workpiece 16 shown as being in the form of a metal sheet. This workpiece is P ice supported on a die 17 supported on the lower shoe 1S of the press. The die 17 is shown as having a die opening 19 conforming to and coacting with the punch 13.

Each stripper spring unit of the present invention includes a stripper bolt 20 having an enlarged cylindrical shank 21 fitted in a bore 22 through the top shoe 11, this bore being provided with a counterbore 23 in the top side of the top shoe 11 to house and form a seat for the enlarged head 24 of the stripper bolt 2t). The depth of the counterbore 23 is sufficient to provide the requisite movement of the stripper bolt 20, with the stripper plate 10, to permit the punch 13 to pass through the workpiece 16 and this head is provided with an out-of-round socket 25 by means of which a wrench can be applied to the head 24 to turn the stripper bolt 20.

The lower end of the enlarged shank 21 of the stripper bolt 24B terminates in an annular shoulder 2S and a threaded downward extension 29 of reduced diameter. On this threaded reduced downward extension 29 is screwed the upper end of a cylindrical nut in the form of a sieve 3@ having an internally threaded through bore 31 of uniform diameter throughout and this sleeve having an enlarged hexagon head 34 at its bottom. The threaded downward extension 29 of the stripper bolt 20 is screwed into the upper end of the cylindrical internally threaded through bore 31 of the nut 30 with the upper end of this nut in firm engagement with the annular shoulder 2S. A helical compression spring 35 surrounds the lower end of the stripper bolt 2t) and the upper end of the nut 3) and is compressively interposed between the bottom of the top shoe 11 and the hexagon head 34 of the nut Sti. This spring is under precompression.

At one side the head 34 of the nut 30 is made out-ofround as by the provision of a notch or flat 36. This notch receives an anchoring pin 38 having a press lit in a bore 39 in the stripper plate adjacent each stripper spring unit. Concentric with the stripper bolt 2t) and nut 30 the stripper plate 1t) is provided with a through bore 40 having an enlarged counterbore 41 in the bottom of the stripper plate. The bore receives the threaded shank 42 of a retaining screw 43, this retaining screw having a head 44 fitting in the counterbore 41 and this head being provided with an out-of-round socket 45 which permits a wrench to be applied thereto for the purpose of turning this screw. A feature of the invention is that the threads of the retaining screw 43 and the downward extension of the stripper bolt Zt are of the same pitch and size and both lit the threaded uniform diameter cylindrical through bore 31 of the nut 30, this permitting standard parts, which are available in quantity, to be used for these parts of the stripper spring unit.

The pins 33 and springs 3S are likewise available as standard parts 4and a feature of the invention is that these springs 35 can be selected or tailored to the exact requirement of the particular job with the result that spring breakage with the stripper spring units of the present invention has been non-existent.

With the stripper plate 1t) supported and biased downwardly by the precompressed springs 35 of a plurality of spring stripper units as above described, with the descent of the ram 12 the stripper plate 10 is brought downwardly into contact with the workpiece 16 on the die 17, this being the position of the parts illustrated in FIG. 1. Further downward movement of the ram 12 and top shoe 11 causes the various punches 13 to pierce the workpiece 16. The punch 13 is illustrated as being a perforating punch and the piece struck downwardly from the workpiece by the punch is discharged through the die opening 19. The invention is not concerned with the type of punch used, however. During this continued downward movement of the ram 12 and top shoe 11, the nuts 3i) and stripper bolts 20 are moved upwardly against increasing resistance of the helical springs 35. Accordingly, during this movement, the heads 24 of the stripper bolts 20 rise in the counterbores Z3, it being essential that these counterbores be deep enough to permit the punching operation.

Upon completion of the punching operation, the ram l2, together with the top shoe 11 and punches i3, rises. The workpiece 16 tends to cling to the rising punches 13 but upward movement of the workpiece under the influence of the rising punches 13 is prevented by the stripper plate which at this time is held down by the compressed helical springs 35. These springs, through the heads 34 of the nuts 3i), hold the stripper plate 16 down in engagement with the workpiece 16 until the punches 13 leave the workpiece i6 and until the heads 24 of the stripper bolts seat on the bottom of the counterbores 23. Thereafter, further upward movement of the ram 12 and top shoe l1 elevates the stripper plate l0, punches 13 and the parts of the stripper spring unit in unison, thereby freeing the workpiece lr6 for removal and replacement.

Each of the helical compression springs has been selected so as to be under preeompression in order to provide the required strength in holding the workpiece 16 down on the die 17 while the punch is being withdrawn, and it is a feature of the invention that the stripper plate 10 can be removed without disturbing this precompres- Sion of the springs 35 and also without disturbing the position of the major parts of the spring stripper units which are retained on the top shoe il. during such removal of the stripper plate 10.

For example, if any punch 13 should break and require replacement, sharpening, removal or altering in position, all that is necessary to change or dress the punch is to remove the several retaining screws 43 which secure the stripper plate lil to the nuts 3Q. When this is done, the stripper plate it) on the die 17 can be removed to expose the punches 13 so that any one can be replaced, sharpened or removed as may be required. It will be noted that during such removal of the coaxial retaining screws 43, the nuts 3@ are prevented from turning by the pins 38 and hence the parts of the spring stripper units, namely, the stripper bolts 2t), nuts 30 and helical compression springs 35, which remain attached to the top shoe 11 are not altered in position. Accordingly, after the defective punch 13 has been repaired or replaced, all that is required is to tit the stripper plate to the nuts 30 and cause the several pins 38 to enter the notches 36 in the heads 34 of these nuts 30, following which the coaxial retaining screws 43 can be screwed upwardly through the bores into the single internally threaded bore 31 of each nut 30.

The illustrated and described manner of locking the nut 34 from turning namely the pin 38 and recess 36, is only one of various means of accomplishing this end.

It will therefore be seen that the present invention not only facilitates replacement or repair of broken or worn punches but also provides a stripper spring unit composed of standard, commercially available parts which has the feature of retaining the properly adjusted position of its parts during the necessary removal and replacement of the stripper plate in order to provide access to the punches.

What is claimed is:

l. A stripper spring unit forming one of a plurality supporting a stripper plate from the shoe of a press and actuating the stripper plate to strip the workpiece from the tools on the shoe following each operation of the press, comprising a stripper bolt mounted on said shoe for limited longitudinal movement relative to said shoe in the direction toward said stripper plate, a nut on the end of said boit projecting toward said stripper plate, a spring under compression interposed between said nut and shoe and biasing said nut and stripper bolt toward said stripper plate, said stripper plate being provided with a through bore coaxial with said stripper bolt and nut, a retaining screw in said through bore anchored in said nut and securing said nut to the face of said stripper plate opposing Said shoe, and means on said stripper plate preventing Said nut from turning, whereby said stripper plate can be removed by merely removing said retaining screws without disturbing the adjustment of any stripper spring unit or altering the compression of any of said springs.

2. A stripper spring unit as set forth in claim l wherein said last means comprises a tlange projecting radially outwardly from said nut and provided with an axially extending shoulder, and a member on said stripper plate engaging said shoulder.

3. A stripper spring unit forming one ot a plurality supporting a stripper plate from the shoe of a press and actuating the stripper plate to strip the workpiece from the tools on the shoe following each operation of the press, comprising a stripper bolt slidingly mounted on said shoe for limited longitudinal movement relative to said shoe in the direction toward said stripper plate, the end of said stripper bolt projecting toward said stripper plate being threaded, a nut having an internally threaded through bore the threads of which mate with and secure the nut on the threaded end of said stripper bolt, a spring under compression interposed between said nut and shoe and biasing said nut and stripper bolt toward said stripper plate whereby the force of each compression spring can be individually adjusted by turning its nut with reference to its stripper bolt, said stripper plate being provided with a through bore coaxial with said stripper bolt and nut, a retaining screw in said bore having a threaded end removably screwed into said threads of said nut and having an enlarged head engaging a side of said stripper plate opposite from said nut to secure said nut to the face of said stripper plate opposing said shoe, and means projecting into said stripper plate and nut to prevent said nut from turning, whereby said stripper plate can be removed by merely removing said retaining screws without disturbing the adjustment of any stripper spring unit or altering the compression or positon of any of said springs.

4. A stripper spring unit as set forth in claim 1 wherein said last means comprises a liange projecting radially outwardly from said nut and provided with an axially extending shoulder, and a member on said stripper plate engaging said shoulder.

5. A stripper spring unit forming one of a plurality supporting a stripper plate from the shoe of a press and actuating the stripper plate to strip the workpiece from the tools on the shoe following each operation of the press, comprising a stripper bolt having an enlarged head at one end and being externally threaded at its opposite end slidingly arranged in a through bore in said shoe with its threaded end projecting toward said stripper plate and with its head arranged in a counterbore of said through bore to limit the longitudinal movement of said stripper bolt relative to said shoe in the direction of said stripper plate, a nut having an internally threaded through bore the threads of which mate with and secure the nut on the threaded end of said stripper bolt, a helical compression spring under compression surrounding said stripper bolt and interposed between said nut and shoe and biasing said nut and stripper bolt toward said stripper plate whereby the force of each compression spring can be individually adjusted by turning its nut with reference to its stripper bolt, said stripper plate being provided with a through bore coaxial with said stripper bolt and nut, a retaining screw in said last mentioned through bore having an enlarged head at one end and being externally threaded at its opposite end with its threaded end removably screwed into said threads of said nut and with its head arranged in a counterbore of said last mentioned through bore to secure said nut to the bore of said stripper plate opposing said shoe, and means on said stripper plate preventing said nut from turning, whereby said stripper plate can be removed by merely removing References Cited in the le of this patent UNITED STATES PATENTS Tobeler Sept. 4, 1928 Kirsten July 12, 1932 Wales Aug. 3, 1943 Ash Dec. 14, 1943 Sokolowsky May 22, 1945 Bennett Apr. 21, 1959 

1. A STRIPPER SPRING UNIT FORMING ONE OF A PLURALITY SUPPORTING A STRIPPER PLATE FROM THE SHOE OF A PRESS AND ACTUATING THE STRIPPER PLATE TO STRIP THE WORKPIECE FROM THE TOOLS ON THE SHOE FOLLOWING EACH OPERATION OF THE PRESS, COMPRISING A STRIPPER BOLT MOUNTED ON SAID SHOE FOR LIMITED LONGITUDINAL MOVEMENT RELATIVE TO SAID SHOE IN THE DIRECTION TOWARD SAID STRIPPER PLATE, A NUT ON THE END OF SAID BOLT PROJECTING TOWARD SAID STRIPPER PLATE, A SPRING UNDER COMPRESSION INTERPOSED BETWEEN SAID NUT AND SHOE AND BIASING SAID NUT AND STRIPPER BOLT TOWARD SAID STRIPPER PLATE, SAID STRIPPER PLATE BEING PROVIDED WITH A THROUGH BORE COAXIAL WITH SAID STRIPPER BOLT AND NUT, A RETAINING SCREW IN SAID THROUGH BORE ANCHORED IN SAID NUT AND SECURING SAID NUT TO THE FACE OF SAID STRIPPER PLATE OPPOSING SAID SHOE, AND MEANS ON SAID STRIPPER PLATE PREVENTING SAID NUT FROM TURNING, WHEREBY SAID STRIPPER PLATE CAN BE REMOVED BY MERELY REMOVING SAID RETAINING SCREWS WITHOUT DISTURBING THE ADJUSTMENT OF ANY STRIPPER SPRING UNIT OR ALTERING THE COMPRESSION OF ANY OF SAID SPRINGS. 